Core making machines are employed to produce sand cores that are in turn used to produce voids or recesses in cast parts. Such molding machines typically inject molding sand into a core box comprising first and second mating core box halves. In such machines, it is necessary to transport the core box into the machine such that it assumes a molding position wherein an extruding or injecting head can be moved into contact with the core box prior to injection of sand. Following production of the cores, and where the core box is of the horizontal parting line type, the drag or lower half of the core box must be moved away from the molding position so that the cores can be removed therefrom. Thus, there is a need to provide some type of transport mechanism for the core box which quickly and efficiently moves the core box to permit rapid production of cores.
When producing sand cores, it is important that the core box be positioned accurately relative to the extruding head. In the past, core making machines have utilized a shuttle car or platform that supported the core box and which was moved by some type of shuttle drive mechanism, such as a piston and cylinder device. However, since the shuttle car, the core box and cores formed therein have a substantial mass, it was difficult to rapidly move the car and core box with the required degree of accuracy using such a device.
In addition to the need to transport the drag toward and away from the molding position, the drag must be elevated into mating engagement with the upper core box portion or cope immediately prior to injection of molding sand and must be lowered away from the cope before the drag is moved away from the molding position. In the past, this was accomplished by elevating the shuttle car and the drag together immediately prior to movement of the extruding head against the mated core box halves. Such a transport mechanism experienced high stresses which led to metal fatigue in the shuttle car owing to the substantial pressures which had to be exerted by the extruding head against the core box and the shuttle car to prevent escape of sand as it was being injected into the core box. Further, the actuator for elevating the core box and shuttle car had to be of relatively high capacity owing to the combined weight of the core box and the shuttle car. Still further, a relatively complex connection was needed between the linear actuator that moved the shuttle car and the shuttle car itself owing to the requirement to move the car up and down.